Climate change is already widely recognized to be negatively affecting coral reef ecosystems around the world, yet the long-term effects are difficult to predict. University of Miami (UM) scientists are using the geologic record of Caribbean corals to understand how reef ecosystems might respond to climate change expected for this century. The findings are published in the current issue of the journal Geology.
The Pliocene epoch--more than 2.5 million years ago--can provide some insight into what coral reefs in the future may look like. Estimates of carbon dioxide and global mean temperatures of the period are similar to environmental conditions expected in the next 100 years, explains James Klaus, assistant professor in the Department of Geological Sciences, College of Arts and Sciences, at UM and lead investigator of this project.
"If the coming century truly is a return to the Pliocene conditions, corals will likely survive, while well-developed reefs may not," says Klaus, who has a secondary appointment in the Rosenstiel School of Marine and Atmospheric Science (RSMAS), at UM. "This could be detrimental to the fish and marine species that rely on the reef structure for their habitat."
The study looks at the fossil records of coral communities from nine countries around the Caribbean region to better understand the nature of these ecosystems during the Pliocene. Today, fossil reefs are often found far from the sea, exposed in road cuts, quarry excavations, or river canyons due to uplift and higher ancient sea levels.
In studying the fossil reefs, the researchers uncovered a striking difference between modern and Pliocene coral communities. The Pliocene epoch was characterized by a great diversity of free-living corals. Unlike most reef corals, these corals lived unattached to the sea floor. Free-living corals were well suited to warm, nutrient-rich seas of the Pliocene. Between eight and four million years ago the origination of new free-living coral species approximately doubled that of other corals. However, free-living corals experienced abrupt extinction as seawater cooled, nutrient levels decreased, and suitable habitat was eliminated in the Caribbean. Of the 26 species of free-living corals that existed during the Pliocene, only two remain in the Caribbean today. The modern Caribbean coral fauna is comprised of those coral species that survived this extinction event.
The scientists argue that the effects of ongoing climate change are reminiscent of conditions present during the Pliocene and opposite to the environmental factors that caused the extinction and gave rise to modern Caribbean corals. So, how might the Caribbean coral fauna respond to a predicted return to Pliocene–like conditions within this century? The free-living corals of the Pliocene would have been well suited to ocean conditions projected for this century. However, the modern reef-building coral fauna may not, explains Donald McNeill, senior scientist in the Division of Marine Geology and Geophysics at UM and co-author of the study.
"Like the Pliocene, we might expect shallow reefs to be increasingly patchy with lower topographic relief," says McNeill. "Rising levels of carbon dioxide will lower the pH in the oceans, a process known as ocean acidification, and will make it difficult for corals to build their limestone skeletons."
Climate change may also increase nutrients in the oceans, boosting populations of marine life that degrade the coral into fine white sand, a process called bioerosion. Reefs built by corals in areas with high bioerosion will be affected the most. Mesophotic reefs, those growing in depths between 30 and 150 meters, have reduced rates of both calcification and bioerosion and thus may be affected less.
The study is funded by the U.S. National Science Foundation. Other authors are Dr. Scott Ishman, Professor, and Brendan Lutz, doctoral student, at Southern Illinois University; Dr. Ann Budd, Professor at the University of Iowa, and Kenneth Johnson, Researcher at the Natural History Museum, London.
The University of Miami's mission is to educate and nurture students, to create knowledge, and to provide service to our community and beyond. Committed to excellence and proud of the diversity of our University family, we strive to develop future leaders of our nation and the world.
Catharine Skipp | EurekAlert!
In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy